The present invention relates generally to the field of numerically controlled manufacturing, and more particularly to a method of digitizing relief surfaces, such as emboss dies, so that such surfaces may be reproduced with numerically controlled machines.
Embossing systems are used to form an embossment or decoratively raised area on a sheet of paper or cardboard. Such an embossment may serve as a decorative feature on a greeting card, business card, or the like. Conventional embossing systems include mateable male and female dies contoured in the shape of the desired embossment. With a sheet of paper disposed between the two dies, the male and female dies are pressed together in complementary engagement with each other. The paper is thereby deformed to have an embossment matching the contour of the dies.
Traditionally, emboss dies have been handcrafted by artists. The artist carves or engraves the surface of a magnesium plate with the design to be embossed. The original magnesium die may be used to make a bake-a-lite copy of the die. Hand crafting of emboss dies requires considerable skill and talent on the part of the artist.
Recently, paper product manufacturers have begun to develop computer-aided methods of engraving emboss dies and the like. Having digitally-defined designs facilitates re-use and it makes it possible to edit and scale digital die designs. Digitally-defined designs also allow for new methods of outputting duplicate tooling based on numerically controlled milling.
Paper product manufacturers typically have a great number of existing, conventionally-created, dies. It would be desirable if manufacturers were able to digitize their existing dies in order to avail themselves of the advantages associated with digitally-defined dies. Currently, however, 3-D scanners are not adequate in terms of resolution, ease of use, or cost, to enable digitization of existing dies.
It is therefore an object of the present invention to provide a high resolution, easy to use, and low cost method of digitizing emboss dies and the like.
The present invention provides a method of copying a three-dimensional surface having X, Y, and Z dimensions. The method forms a translucent impression of the surface to be copied and then captures a two-dimensional image of the translucent impression. The captured image has X and Y dimensions and a grayscale value for each X, Y coordinate of the image. Then, the method converts each grayscale value of the image to a Z height value, thereby generating a digital file of X, Y, and Z values. The digital file may then be provided as an input to a numerically controlled machine, which can be operated to reproduce the surface to be copied. The method of the present invention finds particular application in digitizing handcrafted emboss dies and the like.
The step of forming the translucent impression may be done by pouring a resin that cures to a translucent solid onto the surface to be copied and allowing the resin to cure. Alternatively, the translucent impression may be formed by forming a layer of translucent liquid on a scanning surface and then placing the surface to be copied on the layer of translucent liquid.
The step of capturing the two-dimensional image may be done by backlighting the translucent impression or by scanning the translucent impression with a flatbed scanner in transparency mode.
The step of converting the grayscale values to Z height values is preferably performed by suitable software. One commercially available software system is artCAM Pro(trademark), which is available from Delcam plc, of Birmingham, United Kingdom. The artCAM Pro(trademark) software may be used to automatically create a three-dimensional relief file from an imported grayscale image.